African-American adolescents generally live in objectively poorer environments and are exposed to greater levels of risk. During adolescence, they exhibit lower rates of substance use than their White peers, but this pattern reverses itself through the transition to adulthood. Precocious transitions may be one factor in this reversal. Because poor, minority adolescents are more likely to experience precocious transitions to adult roles, and such transitions are associated with poorer developmental outcomes, including elevated rates of substance use, this study uses two cohorts of adolescents from a nationally-representative sample to examine the timing of race, poverty and socio-cultural influences on precocious transitions and their impact ion substance use in the transition to adulthood. Using a person-centered, life-course approach, I will identify groups of adolescents who share experiences with precocious transitions (transition groups) in each cohort. Next, in the younger cohort, I will identify the contextual factors that predict membership in these transition groups; last, to bridge adolescence and transition to adulthood, I will examine substance use outcomes for the transition groups in the older cohort.